Confused.com

So I started my period this morning but after being up for a few hours. It was red but light.

I went to but tampons and used one..... fast forward to half 4 and I go to change my tampon only to find it's not my usual heavy flow but only a tad red but mostly brown discharge.

I always come on heavily and suddenly I mean I literally feel when I come on and have to go to the ladies. I took a pg test at 11dpo ad was negative so don't think I am pg but this is odd for me. I dunno just isn't normal for me.