Kushya w no answer # 2

The Chok Yackov O. Ch. 489 quotes the Mahril that on the last day of Sefirah you count Hayom Tisha V’arbaim Yom S’haim Shivah Shavuos Baomer Umachroso Erev Shavouos. The Pri Megadim asks , where did the Mahril get this din and why would you need to add Umachroso Erev Shavuos to the counting of the last day of the Sefirah. If you look inside the Mahril you will see that, The Mahril says that on the last day you count Tisha V’arbaim Yom S’haim Shivah Shavuos Baomer . PERIOD- STOP –NEW SENTENCE - Umachroso Erev Shavouos . This is not part of the counting, just telling about the following day. What's Pshat in the Chok Yakov & Pri Megadim ?