Breakthrough bleeding

I've recently (about a month ago) gone back on the pill after taking a break for about 6 months. Im on the same pill as before and it worked great for me for about 3 years previously. This time however I've had breakthrough bleeding the whole month - like a tiny amount of blood but every day. Also when I have sex i bleed a lot more, as if it's my period but afterwards it goes away. It's really annoying and embarrassing! Should I go off the pill or change pills? How long until it is normal again?