Random Spotting

I am probably overthinking this as usual, but irregular spotting has me worried right now. I am pretty regular for the most part - typically have a 25-28 day cycle. Never had mid cycle bleeding other than times I was on hormonal birth control. I haven’t been on birth control of any kind in over a year. I started having more discharge than normal about 2 months ago. Nothing alarming so I just ignored it figuring it would sort itself out. Then this past week, the discharge started looking like it had blood in it at times - a brown/pink color. I am not due to start my period of another week or so. I booked an appointment with my doctor right away and he did a pelvic exam, trans vaginal ultrasound and took a sample of the discharge to look at under a microscope. He said everything looked normal and he saw no signs of bleeding so said it could have been a random thing. I am up to date on both HPV and Pap tests and both have always been normal. I walked away from the appointment feeling relieved, but then 2 days later had more bleeding - this time bright red - after I had a bowel movement. I made sure to check that it was coming from the front end, not the back. I figured maybe I was starting my period a bit early, but no blood the rest of the day after that one time. The following day was the same - no blood or spotting at all. Then this morning, I again had blood coming from my vagina after a bowel movement. Since that, no spotting or anything. I am so confused. I JUST had an exam, but what could be causing this random bleeding. I can’t shake the feeling that they missed something...