My toenails are thick, hard and discolored. it's very embarrassing. is that a fungus? and where does it come from?

Very likely.: Thickened discolored nails that have a powdery and crumbly residue underneath typically indicate fungus. Treatments include topical antifungal therapy such as formula 3 which may be applied to a clean and unpolished nail for 6-11 months. The oral treatment is prescription only terbinafine and is a pill taken once daily for 3 months. It requires lab monitoring to endure no liver issues.

Not always: Try a podiatrist. Your toenails are thick. This can be from trauma in the past or it can be in your family genes. If just the big toe and it falls off then it could be fungus. See a podiatrist. Your right to seek treatment hope this helps. They can offer laser treatment or your doctor can prescribe a medication.

Contact with spores: Fungus can be picked up from walking barefoot, public showers or floors, from shoes. Treatment is with topical and oral antifungals, and lasers. There is high recurrence rate if the source (usually spores in the shoes) is not eradicated.