Daily nausea 6 weeks out - why?!

I'm 6 weeks post-op and as of the last 3 days have had daily nausea after having Breakfast (which is usually Greek yogurt or cottage cheese (vegetarian, no-eggs). I'm drinking Water as I've done last few weeks. I've had an extremely smooth recovery so far but now this has popped up out of nowhere.

I contacted the practice nurse yesterday and she said it could be a thiamine (B1) deficiency (I take Multivitamins every day so that didn't sound right). She said to get bloodwork if it continues.

Has anyone had this happen suddenly a few weeks out? I feel like I'm constantly trying not to throw up (and haven't since surgery).