Since duration of complain is short and pain is postural in pattern it can be muscle. you should take rest,analgesics with muscle relaxant and should avoid forward bending, weight lifting,prolong standing or any vigorous activity. Once pain subsides completely, back strengthening exercises,posture correction and workstyle modification should help in preventing similar acute muscular ache. If it doesnt subside on rest and even on medication definitely you need to see a doctor as well as physiotherapist.they might suggest you x ray or swd or ift but only if your pain remains same even after enough rest and medication.