What should I do (pregnancy help)

I found out a was pregnant 5days ago which I found as a surprise as I would of only been 3 and half weeks pregnant.

But around the time my period was due which was sat I started to get a little bit of back ache and belly ache and started spotting then bleeding lightly.

I have been reading that it could be chemical pregnancy and there is nothing that can be done ?

Should I phone my doctors what would they be able to do ?