My oscar sporadically will swim violently bumping off corners of the tank. I don't know if this is an involuntary act or not. Currently the fish has a large pimple on his chin which i believe has been caused because of the running into the tank. Can anyone help clairify what possibly could be going on?

Welcome to the site. First of all, if the pimple is on the end of the bottom lip, that is fairly common so don't worry about it.

I know what you mean about the bumps and bangs inside an Oscar tank. Oscars will occasionally jump inside the tank and hit the lid. I've actually seen them do this and they were chasing a fly that they could see above the condensation cover. They might see something on the inside of the lid, maybe a bit of dried food, they would jump at this as well. Oscars have actually got extremely good eyesight and are very curious fish so will investigate things they aren't sure about, especially if they think its potential food.

The other thing that happens occasionally is one fish may get spooked causing a chain reaction inside the tank. So you may end with one fish making all the other fish jump, they often swim into the side of the tank when this happens, obviously Oscars are quite big so make quite a loud noise when this happens. From my experience, this is the cause of bumps and bangs nearly all the time so shouldn't really give cause for concern, obviously check for abrasions if it happens a lot. This is another good reason for having large tanks, the smaller the tank, the more chance an Oscar will have of hurting itself.

My oscar did the exact same thing before I moved him into a larger, four foot tank.
It happened usually when I turned on my bedside lamp and the light scared him, he'd then get into a stupor and bash himself very hard all over the tank. I thought this was going to kill him it was so hard.
I moved my bedside light so it didn't shine directly into his tank when I turn it on and having a larger tank helped heaps. He has not done it since.
Do you have any lamps close by to his tank, or have you made and bumps or knocks on or around the tank because this can scare them too?
My oscar bashed himself so bad a lot of times but he just needed a little rest and he was fine. Oscars are very hardy.
Oscarfishlover is right about the oscars getting spooked. I have found they get spooked easily. It's more noticable with oscars as they are so big.
Just watch out for any sharp objects in the tank as he may cut or graze himself on them. Post a picture if you can or put up a link to photobucket.com so we can see your tank.
I wouldn't be too worried as mine did the exact same thing and he's now about 9" and very happy!
Hope you can get some answers!

Also how big is the tank you have at the moment?
And what sort of substrate do you have? (gravel, sand on the bottom??)
What types of decorations do you have, logs, rocks, plants?
I found that some of the plants I have in the tank sometimes brush against Oscar and scare the crap out of him. Silly fish!!

i only have a 30 gallan tank for one oscar, i hope to get a bigger tank soon. Because he so big i only have a two fake plants and a small rock and two plastic shot glass which he throw around alot. I have gravel substrate, but i hear sand is better so i might change to that.

nothing to worry about unless its hurting itself. mine makes loud bangs now and again but im sure its to get my attention as its beside my bed which i use to relax and use pc. now when i hear these bangs i look over and there he is staring at me then once hes one trying to stare me out hel go and get on with swiming and making a mess of one side of the tank then go to the other and clean the plate thats in for them.
maybe its just me thinking hes knocking on me haha

as for the shot glasses some people think there toys but i myself beleive that the oscar will throw them about because they dont want it there. as ive learned they just like to get most stuff out. maybe hes bumping about while getting agressive and trying to shoe the shot glass whos boss.
try taking them out see if it stops
thats my input but dnt swear by it theres alot of helpfull people here kept them and understand them alot more than me
get some piccies up of it in the pics section for us all to enjoy