Thanks for your query.Based on the facts that you have posted it appears that you have a band of adhesion
and glans penis
which pains while retracting your foreskin.
The white thick discharge could be a smegma which is a secretion of glanss located in glans penis.
Please consult qualified Urologist
for clinical examination if the skin tag is too tight it will need to be excised under local anaesthesia so that you can have pain free sexual intercourse and enjoy your sexual life in future.