This is the oddest pregnancy symptom I've come across... Is this normal?

Heh ladies

So I'm in my 3rd trimester and since about two weeks ago I've been getting a yellowish discharge. Usually a lot after intercourse. I've gotten a lot more discharge over the last month or so, but it's a first that I get this tinge, I'm changing underwear up to 3 or 4 times a day and wiping and cleaning down there, sometimes straight after a shower, is this normal or should I alert my OBGYN? Nothing came up from my last urine sample dip stick test.