Extreme dry hair after changing medication- which conditioner?

i am on antidepressant and mood-stabilising meds and my hair has become extremely dry since i changed meds. my hair is curly and prone to frizz, but the biggest problem is that it is dull, coarse and brittle. i do use hot oil before i shampoo and condition but the tubes are so tiny and my hair is very thick- i can get thru half of a 6-pack of oil in one wash. its costly. any good conditioners out there for this?