My 4 Year Old Is Continuously Crying Cause Her Eyes

My 4 year old is continuously crying cause her eyes are burning. Nothing we do seems to help her. She had a low fever 3 days ago and hasnt had one since,but since then she has had nasal congestion and her voice sounds like she is congested, but only when she wakes up, which is all ours of the night. We've been giving her zyrtec and benadryl but doesnt seem to be working. Please help