but what causes shortness of breath?
Benzodiazepines are great muscle relaxers and when we become tolerant to the dose we're on or when we withdraw the drug our muscles react by tightening up. This is a list of symptoms which are normal for this process, I've bolded the ones you've mentioned.
Most Common
Physical:
Muscle pain
Psychological:
AnxietyDepression
Insomnia
Less Common
Physical:
Gastrointestinal problems (may include abdominal pain or cramps, and distension)Visual disturbances (blurred vision, hypersensitivity to light, seeing spots, sore eyes, dry eyes)
Headaches (may include feelings of tightness in head)
Flu-like symptoms (fatigue, lethargy, weakness)SweatingPain in neck and shoulders, teeth and jaw
Limbs feel heavy
Balance problems, dizziness, unsteadiness, loss of coordination
ShakingFeelings of tightness in chest, breathing difficulties, palpations, inner tremblingPsychological:
Phobias (most common are agoraphobia, social phobia, and the fear of going mad)
Panic attacks
Rapid mood swings
Restlessness, jumpinessLoss of memory, trouble concentrating
Nightmares
Irritability
Derealisation (feelings of unreality, changes in perception)
Least common
Physical:
Changes in appetite, weight gain or loss
Constipation, diarrhoea, vomitingDifficulty swallowing, increased saliva, loss of taste or metallic taste, sore mouth and tongue, dry mouth
Craving of sweet foods
Tinnitus (ringing in ears)Menstrual changes
Changes in libido
Urinary problems (frequency, urgency)
Skin rashes, itchy skin, dry skin, slow healing of wounds
Painful scalp
Feelings of 'pins and needles' , tingling or numbness in arms, legs, face or trunk
Hypersensitivity to sounds
HyperactivitySpeech difficulties
Rapid changes in body temperature
Psychological:
Depersonalisation (feeling like you don't know who you are)
Hallucinations
Feeling suddenly aggressive or full of rage
Paranoia
Intrusive thoughts or memories
Morbid thoughts, suicidal thoughts
Unusually sensitive (such as to reading or watching news stories)