DOMS happens to everyone. and it occurs because of wear and tear in your muscle as its not used to rigorous exercise.
coming to the topic.. my younger brother was a scrawny little guy.. wieghing not more than 60...
within a year and a half.. he gained 20kg.. and that too all muscle... then went to pma kakul, now back to 60 
his routine was work out twice daily.. in the morning before going to school and then in the evening after doing homework tution etc..
his diet included half a chicken every day.. 6 eggs.. apart from regular meals.
he didnt take any protein supplement neither steroids.. whats natural is whats best...
so id recommend dont use any supplements.. just vitamins or minerals if you want to.. rest all cover it with your diet...