There is only one spelling for panic; the verb is inflected 'panic, panics, panicked, and panicking’. The form panick is used for progressive tense, past tense and past participle. We don't write panick today, though English speakers from a few hundred years ago might have (in the same way they might have written musick).
When the alternate spelling “panick” is used for the past participle: "I panicked last night at the disco." When it’s use for progressive tense: “Invariably, when markets are panicking, they sell the stocks quickly.”
It's the rule for root words ending in "c" is that you have to add “k”, so the spelling is related with the pronunciation. If we don't add the <k>, it looks as if the <c> has to be pronounced /s/. If the "k" was not there, “panicing” would look like the word which is supposed to be pronounced as if it is ended in "sing," while “paniced” would be pronounced like “panised”.
In Victorian times, many people flocked into the city, the cheap houses were badly built, cold and damp. In London, as many as forty people could have been found living in a tiny terraced house, with ten, or more, people in a single room.
Unable to find rooms, many lived in cellars, under bridges, or even in sewers. Homeless people or drunks out on the street could hire a 'penny hang'. This was a space on a thick rope. Two hooks fixed in the walls, ropes strung in parallel from one side to another at about shoulder height. You would enter the penny hang, after paying a penny. There was no room to lie down. You hung across it. In the morning, the proprietor could come down and untie one end of the ropes, so that the clientele who had not managed to wake up and stagger out already would collapse together in a heap on the floor.