Can I say I dont want to help a person at work?

Unfortunately I have a horrible job of going through old files that are in boxes.

Due to this job I've experienced bad back pain and have torn a muscle in my shoulder.

Another lady is doing this too and is finding it hard to lift the heavy files.

She keeps on asking me to help her. I did before my shoulder injury. It's still painful after 3 weeks and I don't want to make it worse if I help her too. I want to control my shoulder and back problems without helping her which will make it worse.

Is this an ok to say this to her:

"Unfortunately I can no longer help you due to my shoulder injury. If you are struggling let our boss know."

I haven't told my boss about my shoulder cause last time I asked if someone else could lift some, she said "Why would we get someone else to do your job."

If I help this lady, I don't want to get involved. What if she drops the files if I am helping her? I don't want to get involved in that.

Is that an ok thing to say?

I'm looking for a new job but got to stay and do this before I find another one.

Can I say I dont want to help a person at work?
Post Opinion