I just had deep cleaning because gum was swollen for years. will deep cleaning help stop halitosis?

It can...: But it depends on the cause of the halitosis. Periodontal pocketing, cavities, and acid reflux all contribute to your halitosis. If your gums were swollen for years, you may also require more aggressive treatment to treat your periodontitis. Speak to your dentist.

If your problem: Is related to this - it may help. Bad breath may be caused by smoking, dry mouth (due to medications, ^ mouth breathing or salivary gland problems), gum infections, poor dental hygiene, certain foods (like garlic, curry, fish oils or onions), sinusitis, post nasal drip, throat infections, infections in the mouth, bronchitis, lactose intolerance, gerd, improperly cleaned dentures, braces ; retainers.