The light headedness is quite commonly seen in people due to a change in blood pressure that occurs from sitting to standing position. This is also called as postural hypotension
/ Orthostatic hypotension
The only way to control it is not to rush from sitting to standing position.
As far as nose bleed is into the picture. It seems that the blood vessels of your nose have been damaged with regular blowing. I would advise lubricating your nose with some oil - olive, coconut. and reduce the frequency of blowing to allow the injury
If still the above issue continue to bother you then you would need to visit an ENT.
Hope it works, take care.
Orthopaedic & Neurological
Lifestyle Medicine Counsellor