I had an mri done in oct, nothing showed up, my neurologist is sending me for another one next wk, is it possible for stuff to show up later if it didnt show up back then, he was looking for aneryusms, are there different types of mri's or same ones?

Assume your statement is correct there is no reason to repeat an MRI to search for an aneurysm which was not there 8 months ago unless your neurologist strongly suspects you have this problem. MRI can be a regular MRI of the brain with or without contrast or MR angiogram of the brain. Do you know what kind of MRI you had last year?

Best approach: Get a second opinion! Repeating normal testing to see if there is a difference is not appropriate unless a new symptom has emerged. To rule out aneurysm, better to get MRA or CTA. Maybe time to have a virtual consult through HT's paid site.