You can try mucus thinning agents/expectorants. They are available over the counter. For further relief from your symptoms you could do warm salt water gargles and steam inhalations. Please ensure to do this prior to your meals.
Sometimes constant irritation in the throat can cause thick mucus production. This could be due to a sinus infection, a cold or a chronic allergy. It can lead to a post nasal drip and lead to an irritation in the throat. It could be sinusitis, if it is accompanied by nasal stuffiness and facial pain or pressure. Post nasal drip could also be due to allergens. To know about allergic triggers, maintain a diary and note down and monitor your symptoms. This may help to narrow down the search.