Im 13 days late for my period, I did a test about week ago (a cheap one) it came back positive, then I did a clear blue digital 20 minutes later came back negative.
I was confused so went to docs following day and he advised to do it again the next morning with clear blue digital so I did, but came back negative and another one since also negative.
I've has stomach cramps for 3 days last week, my appetite is very odd, I'm feeling slightly sick today and feel that I'm not going to come on
The doctor didn't seem to indicate that they can't help determine if your pregnant and they don't do urine tests anymore, but I'm getting fed up now .
Do docs stll do blood tests and if so should I get one and when should I go.
I just don't feel myself. Please please help. Thanks.

Yes, they still do blood tests and in this situation it would be a good idea. Ask about having a quantitative one, which will check for a level of hcg, a hormone that is looked for to confirm a pregnancy, instead of a qualitative one that simply gives a positive or negative result.
They may have you get one done, or they may have you wait and see what happens when your next period is due in case this period has just been off.