A deep, stabbing pain usually in, around, or behind one eye, is suggestive for a cluster headache.
You may also have a stuffy or runny nose, watery eye, and drooping eyelid on the same side as the pain.
Cluster headache can attack during night, often 2-3 hours after falling asleep, but, it can also occur during the daytime (you may have 1 to 8 headaches per day).
This can be checked for trigeminal neuralgia, too.
Some chemotherapy drugs may cause eye problems, ranging from minor dry eyes to an increased risk of cataracts, and others eye complains like cloudy vision, blurred vision, sensitivity to light, severe eye pain or a sudden loss of vision.

Best wishes!
Marija

Thank you!!! I am in tears. I could not find the answer and was told that chemo has no effect on the eyes. But every symptom you just mentioned I am dealing with. And alot of pain with the light. I am constantly covering my left eye. Especially under flourescent lights like in a grocery store. If you have any further, please let me know. THANK YOU!