According to Ayurveda weak digestion is the root cause of many diseases. Tissues doesn't get nourished properly because of weak digestion, in fact Shukra dhatu gets nourished at last in the order.
Next Steps
Get your semen analysis done, visit nearby Ayurveda sexologist.
Health Tips
Don't use any rasayana/lehya/chyawanaprash at this stage, it's not gonna yield you proper result.