Haha, well first off, I would not say, "I take in about 3000-4000 calories a day." Adding muscle, in my opinion, is harder for most than to lose fat. You need to know exactly how many calories you are taking in. The number one reason why most people, especially skinny people, don't add muscle successfully is simply put, they don't eat enough.
Secondly, that is a general rule around the bodybuilding community that you intake 1 gram of protein for each lb that you weigh. Others will say to take in 1 gram for each pound of muscle that you have. They go on the light side. Others will go as high as 2 grams per lb of bodyweight on the high side.
The point is, each of us are metabolically unique and there are no blanket rules that work for everyone. I would start with 1 gram of protein for each lb you weigh. If you are not getting results, vary your macronutrient ratios. Finding what works for you is like building a puzzle.
I personally take about 1.6 grams for each pound that I weight.