On hair, skin and nails vitamins with 3000 mcg of biotin for at least 4 years now.@1daily for 2 months and then a break.can i go up to 5000 mcgbiotin?

Yes, totally safe: Biotin is extremely safe, in fact there is absolutely no known toxicity from any amount of biotin. 5000 mcg may sound like a lot, but it's the same as 5 mg, which may not sound like much. Whether it helps you is another question; it will help if you are deficient but deficiency is uncommon. Advise continuing the Skin, Hair and Nails vitamin too. See http://lpi.oregonstate.edu/mic/vitamins/biotin