(nsfw) where does an American visiting Europe find a clinic to get tested for std's?

It is my policy to always be tested for stds between lovers. This is not difficult back home in the states, but I am currently touring Europe. After enjoying a one night stand in Geneva, Switzerland a couple nights ago, I would like to get tested asap. I am now in Montreux, and plan to go to Vevey next if that helps at all. I have a lover in Belgium that I will be visiting shortly, and would like to be able to be with him in a respectful, responsible way. Where can I get tested, and what can I expect? Thanks!