Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.
If your hand symptoms are similar to your prior seizures, then evaluation by your epileptologist is recommended, in case the occurrence of your symptoms was just coincidentally related to the massage.
However based on the symptoms you describe, possibilities do include a radiculopathy, or pinched nerve. The spinal cord is encased by bones called vertebra. Nerves start to form as they come off the spinal cord and exit through holes formed between the vertebra. If a nerve is compressed on as it exits through these holes, particularly in an area called the nerve root, a radiculopathy results. The compression could be due to arthritis of the spine or due to a herniated disc or other lesions. The symptoms include pain at the level of the problem (i.e. neck or back etc) and pain that may radiate down the arm or leg (depending on where the problem is). In more advanced cases, muscle weakness or sensory symptoms such as tingling or numbness may occur. A radiculopathy is often diagnosed based on history, physical examination, and MRI of the spine. Most often, symptoms resolve over days to weeks.
Other causes of hand tingling if a lot of pressure was placed in the forearm area is irritation of nerves in the forearm that supply innervation to the hand could have occurred as well (exactly which nerve depends on the exact distribution of symptoms in the fingers; the first three digits would be the median nerve, as occurs in carpal tunnel, the 4th and 5th digit would be the ulnar nerve, and the dorsum of the thumb and index finger the radial nerve).
Rarely, even disorders in the brain can explain neurologic symptoms after a massage (for example, after chiropractic manipulation or massage specifically to the neck area (not the back and forearms), arteries in the neck can be damaged, even leading to stroke). Please understand I am not trying to imply that I think you have a stroke, but should symptoms persist or progress, or new symptoms appear, evaluation by your physician is recommended.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.