I dug a lump from the roof of my mouth now 3 months later it's back mu dentist says it's nothing to worry about but i can't help but worry as it's bac?

See an oral surgeon: Get a referral from your general dentist to a good oral surgeon. He will examine the area and if needed do a biopsy to determine what it is and get it removed.

Lump?: What was the original diagnosis? Go back to the dentist for another look. If necessary get a second or even third opinion from another general dentist or an Oral Surgeon.

What did pathology: of first lump show? Discuss with doctor who took the lump out. You can also get a second opinion.