I was worried about the shaking during my pregnancy as well got an ultrasound and was told that the baby at this stage still doesn't have very good muscle control so what you are feeling are muscle spasms which are normal or hiccups which are also normal.
im 36 weeks along too :) Ive also felt my baby shake before. i assumed its normal. Ive never asked the doc. Ive also felt her have the hiccups. its so cute.
Baby is running out of room so movement is different feeling. You may also be feeling your baby having the hiccups.