Why am I spotting?

Karla
I was recently put on birth control, I've had a hard time getting pregnant (2 yrs) so the plan is to be on birth control for 3 months, lose weight and try again.
I had my period less than 2 weeks ago. I have been on and off the birth control the last week because I have a sore throat and it hurts to swallow anything.
I am spotting. And not to be gross but it's like a mix of normal blood and dried blood.
Is this normal? Any advice is appreciated.