If a colleague is giving you torture in a medical profession, you must be pursuing surgery Ist year PG. Only senior PGs in surgery are known to behave that way. Rarely in other specialties.
Kindly talk to him first, if no response talk to his seniors, if no response, talk to assistant professor, then professor, then Dean. If still no response, give complaint in writing, post it with acknowledgement due.
Do you think you could be depressed as well with all these going on. If so, kindly consult a psychiatrist as well.