Hi thanks for contacting HCM.... You are not able to maintain erection... If you have habit of smoking and alcohol then avoid it as they can lead erctile dysfunction..... If you are overweight then loose weight ... Diabetis by RBS and hypertension by measuring blood pressure ruled out .... Your rectal examination done for rule out prostate enlargement .... Avoid stress mainly ..... Relax during sex.... Do fore play more .... Regular exercise .... Take healthy diet .... The common problem is vascular disturbance of flow or neurological... Sildenafil is phosphodiesterase inhibitor drug that is useful for maintaining erection... You can take sex therapy session for your problem. Consult psychiatrist for it..... Take care .....