Hi and welcome to the forum! I am glad that I can help you.
You want to know the cause of the symptoms that you experience.
Muscle pain may appear after exerting oneself due to exercising or physical work. Individuals may also experience this if they stay in drafty places. This symptom may also appear if individuals who are feeling warm and are sweating, sit directly under the air conditioner (cooler).
Accroding to the data that you described, you may or may not experience any of the medical conditions lised above. Avoid drafty places. You may also consider seeing your doctor for further diagnosis.
Please keep in mind that I provide medical information only. I am not able to diagnose medical conditions online. Please contact your doctor for further advice and information about diagnosis and treatment options.