Suggest Treatment For Erectile Dysfunction

Hello , I am 27yrs old unmarried guy. Last 4 days back, I went to have sex with my girl frnd and it was first time for me. At bed room, m removed her clothes, she became nude and later I have also removed my all clothes. After seeing her, my penis was not standing properly. It stood up for some moment and I pushed my penis into her vagina but only my penis tip went inside to her vagina and it went down. After some time, I tried but i cant do sex, I don t understand. still why penis is not standing up? Before 3-4 months my break up with my ex-gf.. Is that reason was for that ??? May be masturbate was reason for that...? but still I don t know what is proper cause for it I am much worried about it.. what precaution s should I have to take for this problem??? Please help me