High Pulse Rate with sweating.

Hello Dr!            I am 38 year old married woman. I had delivered my second child on 06 Aug 20 in 39th week. It was a normal delivery at a maternity hospital near my home. But had little complications with placenta detachment and so my gynaecologist had carried out manual placenta removal.           Since my delivery most of the time I don't feel energetic, not even able to sit and stand on my own. After around two weeks post delivery my pulse rate increased to 120 BPM and sweats a lot though my oxygen level is around 96-98. I do breathing exercise to bring down my pulse rate to around 80-90 BPM. I was on multivitamins, calcium, iron and protein supplements since pregnancy. But due to high Pulse rate post delivery I have discontinued. Spoke to my gynaecologist regarding my problem but she has suggested to take advice from a physician. Can someone please advise what can be the probable cause and is any testing required.