I know this is going to sound weird, but what exactly did you eat yesterday? (and tell me how you know you ate this if you list mass/volume/weight)
You are going to want to eat at least 1 gram of protein per pound of body weight at the minimum every single day. Then you'll want to just fill in the rest of your calories with a mix of carbohydrates, and fat from decent sources (read:Try not to get it from fast food/junk food, and other stuff like that). Oh, as far as weight gain/loss: Gain weight. No fully grown man your height should weigh less than 165. If you eat one gram of protein per pound of body weight, try to gain about 0.5-1 pound (somewhere in that area) pounds per week, and make sure you are progressing with all of your lifts. Focus on just trying to get strong in the basic lifts (squat, bench, deadlift, row, pull up, dips). If you do that, then you won't get fat.
Also, what exactly have you been doing in the gym for the past month. Are you following any programs? What program switches have you made? How have you been progressing in your lifting? What were you lifting last year, six months ago, three months ago, and one month ago? Not only do you need to eat the protein to gain muscle, but you actually have to try to progress. If I squat 315 for five reps every week, then did three sets of 20 lunges, and some hamstring curls and didn't add weight/reps to anything, and did the same for upper body do you expect me to gain muscle? Of course not. Progress (lifting more weight, more reps, more sets, less rest, better form, etc) is what builds muscle, so you need to put progress as your #1 goal.
So, in conclusion: Tell me what you ate yesterday, your routine, any routine changes, how you try to make progress, your progress since last year, six months ago, three months ago, and one month ago, eat at least 1 gram of protein per pound of body weight, eat to gain muscle, and get back up with us with the information requested so we can give you a better response. \
tl;dr: Don't expect a quality answer in less than 100-200 words.