Sometimes I wake up middle of night with swollen and stiff hands also while feeling my heart beating fast. What could this be from?

Need to see Dr. A variety of conditions could cause your symptoms from endocrine disorders, rheumtological(auto-immune disease), cardiac or kidney problems. You need to start with a primary md or internist to help work out what is going on.
? Not a common association. An event recorder could help determine if you have an arrhythmia as a cause for your palpitations. You have to have symptoms at least a couple times per month for an event recorder to be helpful.