Hi
You might be having performance anxiety,
It's very common. Nothing to worry, with very few sessions & least dose of medicine ( if required) you can get better.
Next Steps
plz visit a psychiatrist or psychologist only if you got distressed because of your symptoms otherwise not required.
Health Tips
whenever you have a talk you can shift your focus, so that it will give you some relief, don't take caffeinated drinks especially on the day of your talk, drink adequate amount of water, join some aerobics or swimming.
all the best,
thank you.