oh no @Crunchymum I saw your other thread earlier but didn’t notice it was you and others had already replied.
the photo looks like the red seal is bulging out yes? I once had a stupid mishap when I rushed and didn’t prime properly, pen plunger wouldn’t depress and I saw it look like that when I took off the needle. I already had syringes at that time so rather than trust the pen again I took that dose and the final one a week later just using syringes. They are a good back up in case of issues with the pen mechanism.
I really hope you can get it replaced but wouldn’t hold my breath for the supplier to agree. If there are still a couple of doses in there - if it were me (not proper medical advice just what I would do) and the red seal isn’t visibly blown, I would store the pen vertical, with the red seal up, under the cap so nothing leaks, and do the remaining doses with a syringe. Not moving the clicks at all. It sounds from your post like you’ve not used syringes before, the UK medi ones someone linked for you are safe and sterile and you should be able to get delivered in plenty time for next week. You can’t store MJ in the syringes it needs to stay in that pen until you are injecting.
given that you don’t know how much was injected it’s probably wiser to ride out this week, or if you really feel it’s not working take the next dose 2-3 days early but don’t take any more any sooner as you might have had more than you think.
However my suggestion is just what I would do if can’t get a replacement, definitely pursue that first reporting faulty pen, and be calm and clear that you’ve used this for over 20 weeks and know what you are doing so it has to be pen not user fault.