Dogs eye swollen shut

Overnight my 13 year old female Great Pyrenees developed a large lump on the side of her face. It has almost caused her eye to swell shut. I am not seeing any noticeable different discharge from her eye. She seems to get relief from me rubbing it. Thinking it may be a tooth infection, however she shows no sign of any discomfort when eating. She also has a large lump on her left side above her leg which I have just assumed was a cyst. This has been there  for a few months and appears to be getting smaller. Her energy levels are good and she seems fine other than this large lump that formed overnight. She sleeps out in the barn in deep hay as it is winter here. My first thought was the hay, did a piece of hay get in her eye. I have given her a Benadryl and am not sure what to do next?
I appreciate any suggestions. Thank you so much for your help.