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Pain involving one side of face could be due to Trigeminal neuralgia, abscess in tooth, exposed root canal, internal ear infection, maxillary sinusitis, TMJ, migraine, herpes (recurrent) without rash or fibromyalgia localized to face.
An eye examination should also be carried out. If all these are ruled out, then yes, it can be stress related.
Do discuss this with your doctor and get yourself examined. Take care!