Please help

Hi I work at pick n pay clothing and I've recently have a new manager. Its clear we don't get along cause from the beginning since she arrived we never spoke to each other. She once called me to the office to ask what's the matter between us and I said nothing cause I never noticed anything wrong with lake of communication. We then started to speak to each on just basic things. Few weeks later my till was short and had an investigation going on to see where the money went and still nothing has been found... Every 10 days I sign forms saying they still investigating me.Since the investigation began I haven't been a cashier for a month now.On the 12th of July I was absent at work because I wasn't feeling well and I reported the matter to my assistance manger because I don't have my manger's numbers.when I returned to work I came back with a Dr's note saying I was a the clinic. I notice this when I signed my hours for the week that my day wasn't on sick day.I made my manager aware that I called in sick and came with a Dr's note she said she didn't authorize it because I didn't call her personal. I told her even if I didn't but there's a note proofing that I was at the Dr and she said she'll fix my hours.A new schedule was formed for August and only to found out the first two weeks I only come to work two days a week.. I asked her why do the rest of my staff members have more hours than me and she just said because I was absent..at work am the only one that spends a lot on transport.. Am pregnant so every month I go to the Dr for a regular check up.I told my manager a month ago that on the 7th of August am going to check up..on the 6th of August my manager sends to my assistance manager to tell me to come to on the 7th.I refused as I made her aware that on that specific date I'll be going to the Dr. Reason am writing this is because we get paid on days that we work.when she reduces my working hours it means I earn less whereby I spend a lot on transport and clearly she's trying to put my job on the line. Please help