In this case, indigestion without belching and heartburn, nausea or vomiting can also act as a sign of an ailment. RIA Novosti writes that sweating for no apparent reason, as well as insomnia and general physical fatigue, can be attributed to the “early symptoms” of a heart attack.
All these signs can accompany a person for several days. But they can also occur suddenly. If a person notices at least one of them, it is worth contacting a doctor for medical advice.