Hi. I'm online and happy to answer your question today.
Since your optometrist checked the contact lens fit and found it to be perfect then I do not think the lens is the problem. As you noted it could be from dryness.
You might try using wetting drops and/or artificial tears in left eye. Also, at night, after you take out your lens, put some nighttime soothing ointment in your left eye. There are many brand names out there such as refresh PM and lacrilube but the least expensive one will work just fine.
Give this a week or two and see if things start to feel better.
Does this make sense to you?
Let me know if I can do anything else to help :)