^^Spotted, I'm not a 'fan' of *bad* farriers OR trimmers, of which there appear to be an abundance, but you can find good brands too!
Faline, yes, pics would help. See link below.
The horizontal crack is most likely from an old abscess, grown down from the coronary border. The main prob with these is if there is infection(seedy, WLD) underlying, and once they grow down near the bottom, if there is too much mechanical pressure on the area &/or general weakness due to seedy, the part below can break off taking a fair amount of wall with it.
The vertical cracks are due to imbalance/excess force on the walls, likely combined with infection &/or lamellar 'stretching' such as in mild laminitis or such. While they *probably* won't get too much worse in 2 more weeks, if they're already half way up the wall, they would have been evident 2 weeks ago when the farrier came, if only to him - perhaps there was only a hairline crack then that you didn't see. Good, well balanced frequent trimming that relieves the walls from excess force & leverage, especially where already cracked, treatment of any underlying infection, which may include resecting, and good diet & nutrition are measures that can be taken to avoid/treat hoof cracks.