looks fungal ..something inside .prob caused by a combination of little things adding up. cut off all dead parts and bits , before surface mould appears. mildue issues....google it,,,,,that didnt happen overnite..yor up take has stopped due to saturation or much toxic salt build up ...get a decent grow book, keep it simple and keep your ph inn check, this is often the first 'happening' in the downward spiral...anyway better luck in the future...and the bugs dont help in any case