Hi With your query, as such, reasons for pimples are many like age i.e. at puberty, due to hormonal influences, type of food you eat and cleanliness of your face are important to avoid pimples.But with your history it looks like folliculitis that is due infection.Then coming to your hard swelling whenever there is an abcess, to drain it the sweeling must be little soft which means that purulent material is ready to drain otherwise with hard swelling it causes pain and the infected material cannot be drained completely.You can also use a cream called erytop for pimples but the ultimate remedy is maintain a clean oil free face.Hope this is helpful.