I don't feel comfortable recommending any online pharmacy that doesn't require a prescription. You never truly know if you are getting the real deal.
If you are having symptoms of something, you should find a low cost or free clinic near you. If you live in the US, call your local health dept, if you are in the UK, you can go to a GUM clinic. Canada also has std clinics.
Its important to test since each std needs a different antibiotic to cure it.