Masturbation, if not done correctly, can lead to sexual disorders. Esp. Erectile dysfunction is very commonly associated with wrong method of masturbation. You must learn and understand about proper method and technique of masturbation. Masturbation is not harmful but doing us excessively, using pornography, doing it to get relaxed, etc are some wrong things.
Next Steps
For specific suggestions and management advice, you can also consult with me directly here on practo.