need to gain wieght and strength

by SC
(CALIFRONIA)

my 18 year has been diagnosed with crohns 3 years ago. she has not had a flare up in those 3 years and was not on any meds during that time...

just last week, she started on Pentasa (1000mg, 3xp/day) because she's had stomach pains and huge weight loss..her crohns is flaring up.

she is already a petite young lady (5' 1")...her normal weight is approx 110-113...she is now at 103 (she lost it in about 3 months).

how can we get her to gain the weight...it is imperative for her, as she is a Division I NCAA athlete on scholarship and obviously, her weight and strength is very important..

any advice?