Thanks for your query.Based on the facts that you have posted it appears that you have developed what is called as Paraphimosis
.which develops due to vigorous sexual activity ( masturbation
This needs to be treated immediately .Consult qualified Urologist
for examination You may need to take injection of Hyluranidase locally to resolve it and will need to take antibiotics and anti inflammatory medicine for a week..
Left untreated or neglected there is danger of developing a constricting band around glans penis