Pimple problem

Patient: Hi doctor..iam 20 years old and i have pimples on my face since 17.. but it has nt reduced till today i hav tried many home made remedies and chemicles like acnil soap,eritop,,benzyol peroxide,etc..but it is of no use plz suggest me some tips to reduce pimples..when i was 18 during my intermediate i got pimples on my back and chest..during those days i used to stay in hostel and the room doesnt have any ventilator…now am studying b.tech and staying in home and so the pimples on my chest and back went off but leaving the black marks of pimples on my back which looks very ugly…plz help me doctor to remove those marks and also are there any laser treatments to remove spots on my back…and also i used to masturbate since 15..i used to masturbate 3-4 times a day…but it has been reduced to once a week..when ever i masturbate iam getting pimples on my face…is tat the reason for getting pimples on my face…and also i hav dandruf problem….plz help me doctor..thanku