Looks a lot more like a dianthus (sweet William) than a phlox. But regardless, it is NOT a houseplant and should be outdoors. I think sometimes I sound like a broken record but plants that are native to or grow happily outdoors in the northern hemisphere make lousy houseplants - it is too dark, too dry and to warm inside a house to make them happy. I'd move this guy outside ASAP and cut back on the watering - dianthus like fast draining soils.

The begonia can go either way :-) These are typically sold as flowering outdoor plants (annuals) for shade or as houseplants. Begonias like quite bright (but indirect) light and are perfectly happy outdoors out of direct sunlight during the summer months. They can be allowed to go a bit dry between waterings....IOW, do not soak them excessively

looks like its got a bad case of spider mites..

but the new growth MIGHT NOT BE AFFECTED...

i cant tell from the pic...

otherwise.. what she said

but what i might not understand.. is spending more $$.. on a plant you bought as a bargain ... if the new growth is affected.. just throw it out... live and learn ...

ken