What is the longest wave you have had with the same symptoms- 18 months

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im 18 months out. i didnt have ANY symptoms from months 14-18 and one day its like my nervous system set on fire. numbness tingling and burning WORSE then i ever had through the beginning and WORSE visual symptoms i have had and they arent going away. i have extreme extreme visual snow , flashing lights, and after images in my eyes, its been here for 4 weeks now and hasnt left and keeps getting worse. im worried about optic neuritis and thinking i should get an eye exam because its not going away