Hi Bright, You could try vitamin B 6 for your dryness, thet say it works wonders for it, perhaps leaving you with a couple of dry days a month.
As for your yellow greenish discharge get tested, try and STD/GUM Clinnic, the staff in these clinics know best its there field, the problem is some of the big STDs can stay hidden, little buggers, if you have a regular guy get both of you tested or things will just go back and forth between you.
One last thing have you thought of trying to change you BC pills, these could be giving you your dryness.
Good Luck
I would get a more complete std panel done. And if you have a partner right now, they should get tested. Some stds can lie dormant for a while, but infidelity might be something to consider. Green discharge is never normal, although slightly yellowish can be. Have you tried using copious amounts of lube? If that doesn't work, maybe a dermatologist would be a good thing to see, since you say it's dry skin that you think is the issue.