When a chameleon's foot is swollen like that it is usually infected and because their pus is thick like cottage cheese it needs to be cleaned out by a vet and a culture and sensitivity test done to determine what bacteria is involved so that it can be put on the right antibiotic.
Unless your chameleon is able to be outside every day it needs a UVB light. It needs to have appropriate temperatures....basking in the low to mid 80's F for a female when not being bred...to aid in digestion and thus in nutrient absorption.
Its important to dust the insects before you give them to the chameleon with the proper supplements because most feeder insects have a poor ratio of calcium to phos....and can o crickets is not a good food source IMHO because they are likely too dry and likely not gutloaded.
We recommend dusting the insects at most feedings with a phos. free calcium powder, twice a month with a phos. free calcium/D3 powder and twice a month with a vitamin powder that has a beta carotene (prOformed) source of vitamin A. D3 and prEformed vitamin A can build up in the system and lead to health issues. Regarding the D3 at the moment, since you don't have a UVB light it would be okay to dust a bit more often to ensure that the chameleon is getting enough D3 until you get the light....AS LONG AS THE CHAMELEON IS NOT GETTING ANY DIRECT SUNLIGHT THAT DOES NOT PASS THROUGH GLASS OR PLASTIC. Also, the most often recommended UVB light is the long linear Repti-sun 5.0 tube light.
Its also important to feed/gutload the insects properly. Insects like crickets, roaches, locusts, superworms can be fed/gutloaded with a wide assortment of greens and veggies such as dandelion greens, mustard greens, kale, collards, endive, escarole, carrot, sweet red pepper, sweet potato, squash, zucchini, etc. Veiled chameleons can also be offered these greens and veggies cut into appropriate sizes for them to eat...along with a little fruit such as melon, berries, apple, pear, etc.
Can you get any live insects this time of year where you live?
As for the humidity, as long as they are well hydrated it shouldn't be much of an issue.
You do need to deal with that foot asap though.