Your dog may have a scratch on the cornea of the eye. This is very painful as indicated by the closed and tearing eye.
Small corneal scratches usually heal within a couple of days. If you have your dog looked at by a vet tomorrow, the vet will most likely stain the eye so that scratches or penetrating wounds can be seen. If the injury is minor, an antibiotic ointment is usually prescribed to use several times a day for a few days. A scratch that penetrates through the cornea can be more serious and need more intensive treatment.
The cold moist compresses are a good idea and excellent first aid. Continue applying them as much as your girl will allow.
Aspirin can be used safely in dogs. Do not use Tylenol, Alleve, Motrin or other OTC meds. The dose is 5-15 mg/lb 2-3 times a day. A 15 pound dog would get a baby or heartsmart aspirin a couple times a day. A 60 pound dog would get a regular strength adult aspirin 1-2 times a day. These doses are based on the low (5 mg/lb) dose. The primary side effect is vomiting, which often occurs at low doses.
Benadryl is useful as a sedative to help keep dogs quiet and not rubbing at the eye. The dose is 1-2 mg/lb no more often than 4 times a day. The pediatric liquid is the easiest form to use in small dogs. It also comes in 25 mg tablets (1 tab for 15-40 pounds) Many people have 50 mg tablets/capsules on hand. 50 mg is a reasonable dose for dogs from 40 -100 pounds.
I do not recommend using eye washes, drops or ointments without having the eye examined first.
Let me know if you have follow up questions.