L-glutamine is an amino acid found abundantly in our blood and body fluids. It is the building block for protein and has an important role in our immune system. Our body manufacture L-glutamine naturally. We also get it from food and supplement.  

I do not know of any literature that links L-glutamine to penile shrinkage.

Sudden and unexpected erectile dysfunction in a young man like yourself is often psychogenic in etiology. Consider any recent events that may have caused you stress, anxiety, depression, guilt, or anger. They may be the triggers. You should seek a medical assessment if the condition persists for over 2 weeks.

Thanks for sharing- just from the description, it sounds like more of a skin condition (eg eczema)! Regarding breast screening- ie. Mammogram, it is always good to check, to ensure that the breasts themselves are healthy. My personal opinion is, the patient has the choice to decide if he or she wants any treatment. Professionally, do encourage her to see a doctor, just so that a doctor can examine and confirm that it's just a skin problem, and not from the breast. Check out my website, and my instagram page for more tidbits of information! @breastfriendsurgery