Started this morning, my arms and lips feels like they have been sunburned but they aren't. there is no other symptoms, just the sunburn feeling.

Sunburn sensation: Not sure what this might be because those two areas aren't closely connected. It sounds like something may be irritating your nerves (disturbing your skin sensation). Often, vague symptoms like these go away on their own in a little while, with no explanation. But, if this feeling doesn't go away, or if it gets worse, go see a doctor. If you get any muscle weakness, go right away.