Asked to wear insoles because of posterior tibial tendonitis. Start to have 2nd toe pain when I walk. What to do?

2nd toe pain. Because of the pain in your 2nd toe, you may have more pathology than just ptt. You may have a tight heel cord that puts extra pressure on the ball of your feet, this could lead to repetitive trauma. Also, the 2nd toe may be longer than the great toe and may be jamming into the shoe. Lastly, the new insole may be taking too much room in the shoe and jamming your foot/toes.
Get it checked. The PTT could be making your gait pattern change which could make the toe hurt. The orthotics may need adjusting as well. See the doctor that dispensed the orthotics.