Itchy Rash on upper body. Other factors?

I've had itch rash (red bumps) few on neck and some on chest area. They itched & irritated a lot the first day, but after having glass of water mixed with curd, the itching stopped and rashes started to reduce & dry. In 2-3 days they were almost gone but took a week or so to completely get rid off. I've not taken any medicines and just increased water intake. Few things to note: 1. I was working 16-18 hours a day during those days and was in immense stress, kept forgetting to drink water at regular intervals so obviously had water scarcity in my body. 2. I've had lots of chicken and boiled eggs (with egg yolk- more than 3 eggs) every alternate day for about 10 days before the rash incident.. 3. I've also had a dental clean up (scaling) 10 days before and not sure I could hv swallowed some tartar :-(. Was also using mouthwash & gum gel during those days. 4. Had lots dates (khajur) What could have caused the rashes - eggs combined with less water intake ? Or other factors? Pics attached