I've always ate shrimp, but today after eating had itching in throat & chin! That went away and now feel like something is stuck in my throat!?

Go to ER. This certainly sounds like it could be anaphylaxis, a systemic allergic reaction that can be potentially fatal, and therefore you should seek medical attention now in an er or urgent care. Once symptoms have been stabilized, you should seek an evaluation from an allergist to confirm this.
Could be serious. Swelling in the throat, tongue, or lips after eating can be a sign of a life threatening allergic reaction called anaphylaxis. Itching on the skin followed by hives can be the first sign. Swelling of the throat can become so severe it blocks your breathing. Wheezing and a drop in blood pressure may occur. Each episode may get more severe, so evaluation and treatment can prevent a worse attack.
Go to ER. This could be swelling from an anaphylactic reaction. These can come on after any exposure to shrimp. Get help asap, this could worsen and result in inability to breathe.