My left nipple is sometimes inverted, should i be worried? No jokers pls...?

yes, i know i need to go to my doctor but i have to wait until next week. I have a 15yr old, a 3yr old & an 8 month baby & i've never had any problems with my until my last pregnancy when i noticed a 'bulge' similar to a varicose vein just under the left nipple. I had it checked out & it was said that it was just one of those funny things that happens during pregnancy. But now, soemtimes the same nipple becomes inverted. I only notice it at night when undressing so i don't know how long its been like that. Its happened about 5/6 times in past 2/3 months, about the time i started taking yasmin (cont pill). Also for past 3 days i'm noticing a 'pulling' sensation similar to the 'let-down' reflex when feeding, also on this . Has this happened to anyone else out there? Should i be worried? (PS i always check my but haven't found anything unusual other than this)