First of all we should learn what does "MASS GAIN" means. In order to gain size or mass, you should EAT more. Protein shakes and mass gainers is just a hype that marketing companies have created. Switch to red meat protein sources such as beef or lamb. That has more fat in it too. Chicken is a lean protein source so dont eat that if you want to put on size. Next thing you could do is lower or stop doing cardio for a week. Make sure your daily calorie intake should be between 2300 to 2700. Stay away from trans fats or saturated fats. Remember, you need to put on lean mass or muscle mass. NOT fat mass. Do clean bulking. Eat healthy food but increase your portion size. Lift heavy weights for your workouts. Keep your rep range between 8 to 10. Try this for a week or so and you can see the changes. Always test and see what works best for your body. These methods might work on my body but not necessarily yours. So always keep testing and see what gives you the results and stick with it. Goodluck