implantation bleeding

Been trying to conceive for 6 months, I had a +ve opk last Tuesday and had been doing the baby dance. TMI I know but....Today when I went to the toilet it was like a red/brown discharge on toilet paper. Been on and off all day (I keep going to the toilet to check). Haven't needed to wear a pad- only on toilet paper. My lower stomach started cramping late afternoon and is still cramping. According to this app my period isn't due until next Tuesday. I've never had spotting mid cycle before. Cramping has been quite constant but not as sore as period pain. 

Do you think this is implantation bleeding/cramping?! 

Feeling a wee bit confused and concerned 😐