I can't get into reverse gear!

On my way down to Laredo Texas from Houston, about 300 miles this weekend, I hit something underneath my car. It was 12:30 in the morning, I was tired so I just never saw what I hit. I am thinking it was a piece of a blown out tire, I avoided many of those earlier in the trip. I heard the slam while I was going about 85mph. It was loud and hard like I got into a wreck. I slowed down, everything felt ok so I finished the trip doing 90mph. I parked the car and it seemed fine. I got in the next day reversed out of the parking lot just fine. The next time I tried to use reverse it won't let me put it in the reverse gear.
My car is lowered and I have the really low slp long tubes on the car with cats and y pipe. I am sure a regular height car would have just flew right over the debris I hit.
Ever since I installed my Long tubes, if I scrape a speed bump the check engine light come on for a while and then cuts off. I assume it has to do with the o2 sensors. The point is at this point I don't know if the hit caused the light to turn on, because it was already on.
I just drove the car back to Houston on Sunday, it is not my daily driver and I am lazy, so I have not even looked at it. I just parked it. So any ideas on where to start looking when I do lift it up would be greatly appreciated.
Thanks to everyone.

M6? Maybe something got the reverse lockout solenoid connector. Something else to check is the ENG SEN fuse, affects lockout too - might have an 02 wire intermitently touching the header somewhere.

Yes it is an M6. Thanks for the help, hopefully you are correct, because I believe reverse lockout solenoid connector is toward the rear of the transmission on the driver side and easily accessible.

So if an 02 wire touches the header it my make the engine light come on?

Possible light, not sure - but if you burn through an 02 wire harness it can definitely blow the ENG SEN fuse and affect the lockout. Just mentioned the 02 harness' cause of your intermitent SES.