If i'm allergic to iodine and i get stung by a jellyfish, should i be concerned?

No: Most people with "iodine allergy" had reactions to xray contrast. This is not an actual allergy (i.e., immune reaction) to iodine, but a side effect of the chemicals in the contrast dye. Even though fish and sea life contain a relatively high amount of iodine, there is no risk for cross-reaction to the contrast material. But, you can become allergic to jellyfish themselves if stung often.