Milk drying up

Hi all! Do Im hoping you can help me. My son refuses a bottle not because its any type of bottle but just because its not my breast. So I have started working half day again. He screams at the person watching him refuses the bottle and basically cries himself to sleep. When I get home I feed him but where I usually have a big supply of milk I feel like my milk is drying up and that can be catastrophic seeing as he refuses a bottle. Any advise please how to get my milk going or to get him to take a bottle. He is 3 months old