1. if no systematic symptoms were there it could probably be due to overexertion, vitamin or mineral deficiency
, lack of fluids in system can lead to an electrolyte imbalance
which in turn can cause the muscles to spasm or cramp. [check with potassium level].
2. if rash and warmth are there and there is bruise like feeling, are you on any blood thinner medications, or it can be a blood clot, seek opinion of general/ orthopedic surgeon for Doppler study [if needed]
3. if soreness was sudden at calf region could be calf strain[gastronemius], following a direct impact to the calf resulting in damage to the muscle fibres, connective tissue
and small blood vessels resulting in a 'bruise' to the calf [calf contusion], a thorough subjective and objective examination from a physiotherapist is usually sufficient to diagnose a calf contusion who may order further investigations such as an MRI scan or ultrasound
to confirm diagnosis.
Investigations such as X-ray, ultrasound, MRI, CT scan, bone scan or compartment pressure testing are often required to confirm diagnosis and rule out other injuries.