Some resources - mostly in German tho... but google translate could be your friend
I can't suggest a specific doctor, but some of these resources may help you find someone. This is how I found the guy I saw in Bern. (Via elpos.ch).
http://www.upkbs.ch/apps/page.asp?Q=954
(the university clinic in basel)
My experience with the uni clinic in Bern is that they do not take self-referals. Primary care doc or someone else has to refer you. Not sure how it works in Basel.
http://www.elpos.ch/beratung.htm - a voluntary organization that helps people with AD(H)D issues and other similar issues. There is a section on adults.
www.elposnordwest.ch/ - for Basel, but a quick look suggests that this is mostly for parents rather than adults with AD(H)D
http://www.adders.org/swissmap.htm
(AD(H)D groups in Switzlerland)
If your German is good enough, apparently there is a community for adults with AD(H)D
http://adhs-chaoten.net - it includes Germany, Austria and Switzerland.
I was diagnosed as an adult just a few years ago. I wanted to understand something about how my mind works, and how I process information. I don't feel I have a disability or a disorder, but I know that I operate differently than many people, which is fine. I went back to grad school as an adult and was having some problems getting work done - the diagnosis allowed me to use some of the services at my university, and to restructure my program. It also allowed me to use an ADD coach at the university. There are obviously different sorts of coaches - this was a practical, skills-based, program and it helped me learn to appreciate structure, and implement organization that I can live with. I found it very useful. There are specific AD(H)D coaches in Switzerland, but I don't know how they operate.
The diagnosis process also helped me understand my strengths and weaknesses.
For me, ritalin has been incredibly helpful, but I can't take the longer acting versions. I have terrible test anxiety, something which has troubled me in academic and medical settings. Ritalin relaxes me. I don't have negative side effects that I'm aware of. But that's just me. At any rate, I don't feel it controls me.
In Switzerland, my primary care doc prescribes my ritalin. I went to see an AD(H)D specialist in Bern, which satisfied my primary care doc. That plus my testing profile from the US. I didn't like the AD(H)D specialist, and found it difficult to work with him. Probably when I move to Zurich next year, I'll find someone else for the occasional follow up. Of course, right now, I have other health issues to deal with.
If you have a primary care physician, you might ask him/her for a referral. Some of these docs might require a referral, I don't know.
AD(H)D is quite real for me. I'm glad I understand more about it, and I'm glad I've an effective treatment.