It sounds like your baby has hiccups :) mine has hiccups almost everyday lol.
Sounds like you are experiencing Braxton Hicks, your body is having "practice contractions" I had them at 30 weeks with my first son. It's normal and unless the pulsing starts to get progressively stronger and are at regular intervals then call your dr. I would still inform your doctor that you are feeling Braxton Hicks to keep them up to speed with what's going on :-) good luck!!
Lol it can be just you finally being able to feel your babys hiccups. I started feeling the throbbing a littlw after 30 weeks and when i finally asked my midwife she confirmed they were just hiccups. As baby gets bigger his/ her hiccups become more defined. :) feel free to ask at your next appointment anyway for reasurrance. Im sure everything is fine