Sebaceous cyst or Scalp condition

I have always had healthy hair and nails just like my mom did. I have vey thick, curly hair that is coarse like most curly hair but healthy. About a year ago my hair became very dry and was falling out all over the place and sometimes came out in very small clumps (like 20 strands in one place). My hair is very thick so it wasn't noticeable like balding or anything. It was breaking off too, overall very unhealthy. I had just turned 40 and my normally dry skin had become a little oily on my face etc so my doctor blew it all off to aging. I took my hair in a ziploc bag to show her how much was coming out in the shower because I was concerned. Over a period of about a year or year and a half it started with hair loss, then became dry and breaking, then started turning grey. No one in my family had pre-mature grey and none of the women were grey but I blew it off to "stress grey". It would get better and then I would get a lot of grey again so I believe it is stress. Also because I have and had been extremely stressed, depressed etc. I have been taking care of parents with cancer, alzheimers etc for 10 years and I own four businesses and had 5 deaths of loved ones in just a few years from my daughter to my father. So, very stressed to say the least. Now I have these bumbs on my scalp. I have had sebaceous cysts in the past and just recently had one cut out of my chest. These bumbs on my head are the size of a quarter (large, thick and hard) and the center is soft. The center is soft like a big water blister but the inside is waxy like a sebaceous cyst. I have been using a tar shampoo for about two weeks and it isn't going away. I can not leave it alone! It doesn't itch but I can't quit picking and scrubbing at the waxy residue.
This could all be stress and diet related. One thing that I am worried about is the water in the house where I live. I bought this house two years ago. I have six dogs ( I rescue animals) and they are having problems with their skin, allergies etc. After about a year my dishes would come out of the dishwasher with a shiny residue. I put vinager in my dishwasher but it didn't help. Later I discovered that the house has a filter on the water supply where it comes in the house. I immediately had someone come and change it and the residue on my dishes was gone instantly. I can't help but wonder if that wasn't the start of my scalp problem and my dogs health problems. The filter was full of sediment or something and obviously it was getting in the water. Has anyone had this problem? Does anyone know if this water filter could have been the cause? Oh, last question, Has anyone had or heard of this problem? I will be extremely grateful for any help. Thanks in advance.