Can someone give me any idea to what is going on?

Ka
I have irregular periods. My last period was 20th - 24th July, it's normally a medium flow and I have to wear sanitary towels. Recently from the 6th October I have had a small amount of brown blood (looks like when a period ends) on my tissue, only when I wipe. It's not not enough to wear any protection. This lasted for about 3 days (6th - 8th), it's the 9th today but but so far no blood, there could be a possibility I'll have it again later through the day since it hasn't been a constant flow. 
I took a test (Clearblue Plus+) about 6am this morning because it was bugging me that maybe I could be pregnant but it came back negative :(
Has anyone else experienced this before? I wouldn't call it a period as there's not enough to use a sanitary towel, the blood isn't red or pink, just brown. It's just not like any of my normal periods.