Fear that I might have been fired from work due to reporting pain in leg

I recently started a new job as a scientist in a factory. However, having started there I've become aware that my lab isn't set up yet, so they've put me doing other jobs.

This week I was put doing a job that involved lifting pallets out from underneath a 1 tonne bag (lifted by a fork lift) and then dragging them a significant distance. Anyway I woke up yesterday morning with a sore left groin. I didn't know why, or have much time to think about it, but when I was put doing this task again yesterday (third day of it), it made sense how I got the pain. The position I was in and the movement required was clearly what was causing it. I didn't feel I should have to continue.

It was a hard decision to make but I decided to notify the lab supervisor that I had a pain in my upper thigh. After all that what we were informed to do during our H&S / manual handling induction talks. I think she was a little suspicious when I notified her of this. I had already mentioned another safety concern I had to her two days prior, and that was about the proximity of the 1 tonne bag.

Later on, by chance, I saw this supervisor bump into the guy, who was working moving pallets with, in the yard as he was going for his tea break. I saw them talking for a bit. A few minutes later, I went for my own tea break and after a while this supervisor stuck her head in the door looking for me. When I went out to her she told me that the head manager said to take the week off (unpaid)! I replied "I'll take the weekend off and see how I feel". She eventually said that the main manager was over in her office and that I could go over and see her.

So I went over and had a quick chat with the manager. She didn't seem like she wanted to even know how this happened to me, nor did she take a note of it. At one point she said "well, it's not the factory's fault... people have been doing job like that for years and have never had any complaints". This is the same factory where someone had the top of their finger chopped off a few weeks ago.

There were four other science grads taken on full time the same week as me and none of them are doing repetitive physical work. I also know from having spoken to the supervisor that she doesn't even understand what the job that I was doing involves! The manager made the excuse that the only reason I'm doing this task is just to get a sense for what's going on so I'll know where such samples come from when their sent over to my lab. That's complete nonsense. They're using me as a store house worker even though I was hired as a scientist.

Surprisingly it's feeling a lot better today, but that was only because I took the precaution in stopping early. I'd like to know what employee rights do I have in this situation. I think I'm going to show up on Monday and clock in, and request that we sit down and have a talk about my situation.