Hi there and thank you for your question.
I can appreciate your concern regarding this issue and I'll try to help you were I can.
Judging by the symptoms you have noted in your inquiry, it sounds as if you might have a
fungal infection of the head of the penis. This condition is called fungal
balanitis and caused by the fungus Candida albicans.
Now, candida is a normal fungus found in the vagina and is present to help with regulation of the normal organisms found there. If your girlfriend had a fungal infection (colloquially also known as 'yeast infection'), then it could be a way that you have been infected with this fungus. it doesn't mean that your girlfriend gave you an
STD but rather a common infection women get via the sexual intercourse route.
You can ask your pharmacist for
clotrimazole cream and apply it liberally to the head of the penis 2 times a day until the issues resolves or for a maximum of 14 days. Once the symptoms have resolved, then continue applying the cream for another three days so as to make sure you kill off all the fungal spores so that this issue doesn't recur. Before applying the cream, just make sure that you have cleared as much of the discharge from the head of the penis as possible.
If the problem still persists then you should consult your doctor as you may need to have this condition treated with
oral antifungal medication.
I hope this helps and good luck.