Sneezing Pup

We adopted Liddy (mix breed) from a rescue organization on Jan. 3rd. She is currently ~4.5 months and 23lbs. Not long after we brought her home (3 days or maybe 4) she started sneezing. She sneezes after every nap and often when she sniffs around outside. Eye goop shows up after every nap too. The mucous is serous and she seems to have no other symptoms--eating, drinking, eliminating, playing and resting as we'd expect. We tried Benadryl (1mg/lb body wt) as per our vet friend, but I don't think it made much of a difference. She is not coughing. I think the congestion might be worse today than it has been in recent days. Should we consider going to a vet or wait it out? Any other info you need to know in order to answer the above question?
Thanks.