hello and welcome to HCM,
A nose bleed is like a headache; which means that there can be many causes of the same. However in your partners case it may very well be because of the snorting drugs though there is no better way of finding it out other than his own confession! If he is very sure that there is no snorting involved then you need to do the following and rule out other causes one by one:
1. Get a complete examination of the nose to rule out a condition called the deviated nasal septum
which can cause the bleed.
2. Get a full blood check up including coagulation profile which can rule out any bleeding disorders. Also ask for the thyroid
profile in consideration of his weight gain. You may also ask for a drug screen which can rule out the abuse of common drugs.
3. Get an CT PNS and endoscopy
of the nose to rule out other different cause of nose bleed such as polyp or tumour
take care and do not allow him to blow hard on his nose and also try steam inhalation
Dr Sriram Nathan