Your Lumbar region is in your lower back, from the area of your waist down. So If your upper spine is bothering you, it's definitely not Lumbar.
Thai Massage deals with stimulating pressure points (accu-pressure of a kind) and stretching. Sometimes after a massage, some minor inflammation may occur.
When you next see your massage therapist let them know your problem so they will use less pressure in future.
To relieve the inflammation you may try taking 4 x 200 mg tablets of ibuprofen every 6 - 8 hours. But if you're not feeling better in 2 days, see your Doctor.