so my car drives normal when im driving normal. 1st to 5th everything is good.
the problem is when i'm pushin my car. when i push my car i go as high as 6k rpm. 1st and 2nd gear & 5th is fine. but for 3rd and 4th gear after 4k rpm, the gear shifter starts shaking all violent and aggressive like. it started happening to day and im wondering if anything could be wrong with my tranny. (midlands 5). i'm worried cuz if it is my tranny , then i will be a heck of a lot of $$$ poorer

any help or advice would be GREATLY appreciated!

edit 1/7**
omg now the whole car vibrates at high rpms in 5th gear!
like on the freewway. but only when i press the gas pedal.
what the ef is going on'??