Implantation bleeding or period?

So yesterday I had very light, brown discharge all day.

Today I had red spotting blood earlier. 

Then when I went to the toilet this afternoon there was a bit more blood in the toilet bowl and when I wiped myself the tissue was reddy pink. No blood on my pad or knickers though.

This evening I went to the toilet and there was nothing there at all. Now I've just been again and there is some bleeding but light, still not like a normal period and mine are usually quite heavy.

I had sore breasts last week for a few days too.

Do you think this is implantation bleeding or my period?

Why would it be a strangely light period if it is one and why would it keep coming and going throughout the day?