Can my boss require a Drs. note for an apt. after the apt. to approve sick day

My boss informed me after my Drs. Apt. that I would need a Drs. note to receive a paid sick day & a Drs. note for any future sick days taken because I had been sick too many days although there is no written policy. Can he legally do this? I have also received this notice in writing along with saying failure to provide this will result in loss of pay for that day & possible further consequences. I work for a smal school district as a para-professional & have never been required this before. During the school year working with kids there are many times sickness goes around & staff & students are both out sick. During a 4 day flu bout I had a month ago, several other staff & students were out also. He asked me if I was happy working there & I asked why was he asking me this & he said because I had been absent from work. I told him I'd been sick but he didn't seem to believe me. I've had some issues with him, my boss & another teacher when asking questions regarding my schedule being changed while I was out sick & some of the meetings have been some what contentious so i have taped a few conversations for my own reference. I sense he's doing this because he'd like to fire me or have me quit. I really don't want to continue working in this hostile work environment but don't want to give him the Drs. Note but would like to be paid. I also wanted to give a 2 week notice but then I do not think he would give me a good reference so do not feel compelled to give him one. I also have several sick days accumulated over 5 years that will be loss. Thanks for your help.
Sincerely, Donna