Thanks so far for your help. It could be something with parasites. I will check out the cleanses and detoxing protocols.
Another symptom I didn't mention is mild tinnitus that I have since the age of 17. Luckily it is very mild and I hear it only when sleeping. This last year I also noticed some difficulty hearing people in environment noise.
I also suspect it has something to do with malabsorption/deficiencies. In march this year I had a bloodtest done, with overall some minor deficiencies in B vitamins and minerals. I'm trying to incorporate more nuts in my diet.
To me the symptoms look copper/zinc related, but I'm not sure. In a few weeks I will have a more detailed blood test done and also test for copper/zinc and ceruloplasmin (copper binding protein).
I will check for celiac, but I don't notice any problems with digestion. If some of you have other suggestions I would like to hear it.