Thrombosed external hemorrhoid treatment

I have had a lump in the anal region for 14 days. I have been taking the medicine Calcium Dobesilate and Pilorute cream these 14 days prescribed by a gastroenterologist who diagnosed me with external hemorrhoids but with very little improvement. Recently, a colorectal/general surgeon diagnosed me with thrombosed external haemorrhoids and needs surgery. He also diagnosed internal haemorrhoids at 3, 7 and 11 o clock positions which he said won't need surgery. The external haemorrhoid is pea sized and doesn't hurt. However, I wanted to know: can thrombosed external haemorrhoids go away on their own with meds or do they always need surgery? I saw an article by a proctologist that says even in case of thrombosed haemorrhoids the lump remains present for up to a month and eventually gets reabsorbed by the body. Is that true?