Could be, or it could be that your own cycle plunged which for me accounted for increased joint pain etc towards the later stages of peri. It could just be your own hormones dong their thing! It's a minefield!
If you are getting a bleed on the 25th day regularly that could be your own cycle which in peri often reduces early on. When on HRT my own cycle was completely erratic, 9 days upwards, some months I had 3 bleeds, one HRT induced and two short cycles of my own. It was horrendous.
If I were you I would chart, keep a detailed daily record. Every specialist I saw insisted upon it. Don't get bogged down with detail, just take three mins each day to record what is happening. i.e. swollen breasts, bloating, changes in mucus, joint pain, any bleeding however minimal, ovulation pain etc etc. A story will emerge quite quickly.
Good luck to you, this is such a trying time! x