This is either a form of seizure or collapsing episode (syncopy or other). This problem needs to be investigated. Your vet will need to take bloods to make sure there are no metabolic causes for the problem and I would also recommend an ekg / ecg if collapse episodes are thought to be heart related.
The problem does sound more like seizures (epilepsy is a condition leading to seizures) although typically seizures occur when becoming active after a period of rest (most seizures occur when pets wake up).
There are medications (phenobarbitone, potassium bromide and others) that can be used to control seizures.
A magnetic collar wound do no harm but I would suspect it would not be enough to sort the problem and this problem really needs to be investigated further.
Hope that helps, David