I have also noticed the very symptoms you listed after I have been on my cell phone for a while, and it actually concerned me until I realized that it wasn't because off exposure, but the way I was holding the phone while I talked. Before I started using my headphones for every phone call, I used to sit with the phone pressed against my ear, and as the conversation carried on, I would usually lean on my elbow with the phone pressed even harder against my ear. After the conversation ended, my ear would feel warm and numb, and I would have a tingling sensation in my hand and the side of my head.
I brought it up to my doctor and he told me that it was most likely caused from the way I had the phone pressed so tightly against the side of my head during longer phone calls. He suggested that I use headphones or an earpiece, and it fixed the issue for me right away.
I have an answer to your tingling fingers don't know about your head Long cellphone use leads to Cubital-Tunnel Anytime you keep your elbows bent an angle of more than 90 degrees, you stretch the nerve that goes up the arm around the elbow. Here's a quick article on it. Read the March 2nd posting.
There is the possibilty that because its hot your phone heats up more and therfore you notice it more. The major reason that people have tingling from phone long phone calls is that they spend time either wedging their ear and shoulder to the phone which compresses nerves and also they spend a lot of time in a forward head posture whilst on the phone. This " 'forward head posture is the major cause of neck pain, disc bulges and pinched nerves" Mayo clinic.
I have written a lot about this on my blog www,neckpainexercises. Com I hope this helps.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.