You already leveled your CNJ so you should at least equip cure on your action bar when playing any of the above mentioned classes that you are having difficulty staying alive with solo. Then you could lvl THM just a few levels to get some nukes, which I would also reccomend equipping on your action bar. As PGL or PLD you have decent MP, so you may as well make the most use of it and your cross class cures and nukes- it'll make killing a mob much easier and quicker.
Solo to 50 really isn't that tough with leves. Plus, now you can get rested exp at the inns which effectively double your exp gain + food for an extra 3% gain. If you have a problem surviving a leve, either you chose one that is too high of a lvl, or you added too many stars.
