Are there any supplements available for bone strengthening for kittens? if not are there any alterna

Im curious because my kitten wasnt with her mother very long and i notice that when she is going to the litter box to take a poop its hard for her to stand very long without falling and getting dirty...i just wanted to know if its her bones and if there is something i can do to help her..P.S. im giving her Cat & Kitten Vitamin paste...but im not sure if it promotes healthy bones, it just say it promotes healthy eyesight. 

Has she had a vet check at all? Usually by the time kittens start using the tray at 3-4 weeks they are steady enough to not be falling about in the tray.

i wasnt going to make an appointment until i knew for sure that she needed to see one...but if she needs to see one i will see if i can get her in tomorrow..

More likely this is not a bone problem and rather a neurological problem.  How old is she?  What does she eat besides the paste?  Was she ever on the Hartz brand of kitten formula?

How old is she now? What do you feed her (list everytthing, even treats)?

she is 4-5 weeks old but i dont know her exact age because i took her in about 7 days ago..and she looked very malnourished but since i've taken care of her shes gained a very healthy amount of weight. i was able to contact a vet and when i explained to him what exactly was going on with her, he said it sounded like a calcium deficiency and he gave me a special recipe to make and give to her and have her have it with every meal..he said that they use it for the stray kittens that they get especially because they are weaker.

i feed her every three to five hours. i usually put the paste in her formula,(PetAg replacement milk) which was recommended by the vet. along with a small amount of solid food. i dont give her treats, because i dont want them to upset her tummy...but thats pretty much it.. 

At this age she should be eating more solids, maybe 2-3 ounces a day. . .try a canned kitten food (Fancy Feast, Iams, Wellness, and Nutro are brands I know of) and mix some of the formula in. I can have most orphans off the bottle by 5 weeks.

What's in the special recipe the vet gave you? If he already gave you something for her bones I don't think it would be a good idea to add anything else.

i dont add the paste to her food anymore. and i am feeding her canned food but if i give her too much it gives her diarrhea.

What make food is it?  That could be the problem rather than the quantity.  Has she been wormed?

i have been giving her 9lives...she loves it, i tried giving her other brands but this is the only brand she will eat...