Are recurring health problems in the family and the husband leaving his current job to work daily in agriculture in search of lawful sustenance a punishment or a test from Allah?

Affliction befalls a person according to the strength of their faith. The most severely afflicted are the Prophets, then the righteous. This is for the elevation of ranks or the purification of believers, and it is not always a punishment. If the husband's work does not involve usurious transactions, there is no need to leave it, and he should seek the cause of the illness and its cure.