If I am severely dehydrated, do I need to seek medical attention?

Yes. Dehydration, especially if severe, is a condition that can cause confusion, organ damage, and death. Seek care if you are in any way concerned about dehydration.
Yes you do. If you are severely dehydrated it is a medical emergency as it can lead to kidney shut down, fall in blood pressure and electrolyte imbalance which if not corrected quickly can be dangerous.So if you are really severely dehydrated go to er get evaluated and treated with IV fluids and avoid the complications.
Depends. If you become too dehydrated you may not be able to adequately hydrate yourself with oral intake and need an iv. Many athletes such as football players go into the locker room and get an IV to rehydrate. The best treatment is not to get dehydrated. Make sure you have ready access to fluids: water, gatorade.If you find your body getting too hot then you need to drink plenty of fluids asap.