Car is shaking

[Warlord55]

My car(2002 GP SE) always shook a bit at around 70-75mph. Yesterday I was driving at night and I hit something in the road with my left tires, it looked like a sheet of metal or something flat. Anyway after that it started to shake even more at 55-75 about 3 times as bad. It also get worse when slowing down and turning right. I looked at the tires the rims and anything else I could think of, but I couldn't see anything wrong with it, I also had someone look at the tires when driving and they look fine.
I don't want to take it to a shop and get charged with something I could fix.
Anyone have any clue on what this could be?

[Dtrick22]

Since you say it always shook around 70-75 you can start with getting your wheels balanced. Then take it from there

[Warlord55]

So do you think that hitting that thing in the road might of "unbalanced" the tires even more?

[gtpinsc]

feel for bubbles on the inner sidewall.

[Whiplash Performance]

Check your:
Tire pressures
Lug Nuts
Motor Mounts

[GAFF]

Check the hubs also.

[squeaks130]

Balancing would be the first thing I would try, when your car hit the metal it coulda knocked a wheel weight off. Re balancing usually isn't too much, and its something that you cant do yourself.

[SuperSport]

Balancing would be the first thing I would try, when your car hit the metal it coulda knocked a wheel weight off. Re balancing usually isn't too much, and its something that you cant do yourself.

Was just going to suggest this.

Make sure your wheelweights are still there...

[Warlord55]

Well I went to get my tires balanced. When they looked at them they saw that two of the tires are starting to separate. So I had all the tires balanced and had them put the bad two in the back, since the tires only have 20k miles on them. The shaking basically stopped and I'll just get new ones when it gets worse.
Thanks for all the input.