Since Miguel is out at the field under the hot sun working hard practicing football, it is likely that Miguel is exhausted and very much tired. The water content in his body has decreased drastically. And also since it is very hot, Miguel is likely to suffer from heat stroke as his body temperature has increased at a rapid rate and he is suffering from fever at 140° F, which is a clear sign of heat stroke.
Heat stroke is a most severe heat attach where the body temperature rises upto 140° F or 40° C or higher. It also leads to body cramps, vomiting and severe headache, increased pulse rate. This is very dangerous and may lead to death. Therefore it is very important to take medical care as soon as possible.