Sick Budgie

Recently my male budgie has gotten sick. It is shivering, its feathers are all fluffed up, and it's eyes are constantly droopy. However, at the moment I am not in the best financial situation to take him to the vet. He is sticking very close to my other female budgie, maybe to maintain body heat? What can I do to help him get better? I really want to take him to the vet but my money situation is not it right now.