Is it okay to receive a muscle relaxant injection when you have a stiff neck?

In the morning, I had difficulty turning my head and experienced severe neck pain when trying to tie my hair, so I just tied it loosely and went to the hospital. I had previously received a muscle relaxant injection in the trapezius muscle at the 21st Century Orthopedic Clinic over ten years ago, so I went there to get an injection. However, the doctor looked serious and said he doesn't give such injections. He said that if medication doesn't work, they can perform treatment similar to an ultrasound-guided injection, but it's a bit expensive. He told me to try medication first and come back if it doesn't improve. I received physical therapy such as electrical heat therapy and was prescribed medication. At home, I keep massaging my neck and shoulders with a massage device. But no matter how much I think about it, I don't understand why they won't give me a muscle relaxant injection.

These days, do they not administer muscle relaxant injections? The doctor was very firm and said they don't prescribe such things. I used to get them before, but now I ask not to be given those, and I felt really upset that they don't give them anymore. Is it not okay to give muscle relaxant injections casually? The doctor was unfriendly, so I thought I shouldn't go, but since it's nearby and urgent, I went again. Next time, I don't want to go.