Postpartum nausea

I’m 4 months postpartum and have been having sporadic feelings of nausea. My whole digestive system seems sluggish or off, I rarely feel hungry, if I eat a snack after dinner I wake up feeling awful indigestion and I’ve not only lost all my pregnancy weight but an additional 10lbs. People are starting to comment on my weight and I think I’m starting to look sickly. My bowl movements haven’t been normal for a long time, and I have the urgency to go similar to when you’re on your period. I also feel extremely fatigued snd low energy again and missed my last period (I’m on the pill and have had two normal periods so far). i took a pregnancy test and it was a very clear negative. Anyone else have anything similar? Is this normal after giving birth or should I see my doctor? I’m a ftm