Normal or should I call his doctor

Katherine • Mother to mason 12/2/13 maddox 5/22/18 Wife to jeffrey 10/10/15

My son has issues gaining weight due to severe acid reflux since he’s been a newborn. He has been battling a head virus for the past week (not really been interested in eating his formula but I’m not making enough breastmilk for him to thrive off that alone but I’ve been trying to get him to eat formula too). My question is if he’s dropped a pound in a week should I email his doctor? My mom and husband think it’s normal for weight to go up and down and since he’s been sick he’ll gain it when he’s better.

Sorry if this is all over the place I never dealt with the acid reflux with my first born.

Note he sees his G.I. On monday