I'm not sure you can get any additional med to realistically do what you seem to wish for;
that is to lower your pain and allow you to have more abilities, when the little one is there, without making you too unwell to care for him.
I'm Not sure you can do all the movements you usually do with him, either, without exacerbating your back condition, and also without increasing your need for and subsequent hope for an additional med, that could help without adding more side effects.
I would think about changing lots of the ways you do things, when he's there, instead.
Also keep in mind, that while a pharmacist knows lots more about the meds, (than us or you or your doc, etc)
they will not be free to advise any suggestion that counters ANYthing the doc has told you or ordered for you to take.
You could get some useful input from them, but they will not tell you, if it would be best for you to make a change altogether in those meds, either that one or the combination, or to go to a different doctor.
Consider also, to make some changes to your ongoing daily regimens (both when he's there and when he's not)
to include more repetitions of non-med (proactive) pain and health actions,
such as frequent rests, and heat and cold, and other body positions/gentle motions, etc, etc....
These are all just ideas for you to consider; of course, can't give any medical advice here.