I keep on losing weight while trying to gain weight and eating alot.. how can i fix it?

Weight Gain?: How much weight are you talking about and what is your weight to begin with? There are metabolic conditions, specifically an overactive thyroid that can cause this that should be looked at by your doctor. Parasites can also cause this. Also consider the type of foods you are eating and your activity level, a balanced diet is going to be the best.

Recommendation : The first of all you need to know why you loosing weight. You need doctor's appointment and maybe some tests to figure out the cause. If no real medical problems your diet need to include high calories food, like pasta, cheese, butter, peanut butter, fish.